This application for supplementary funding to the Baylor College of Medicine Mental Retardation Research Center seeks to establish a collaborative Fragile X Syndrome Research Center composed of investigators at Baylor College of Medicine in Houston, Texas and Emory University School of Medicine in Atlanta, Georgia. The application seeks funding for four investigator-initiated research projects and two core facilities. The four projects will revolve around a common theme of delineating the full spectrum of phenotypes and their underlying bases in humans and mice with genetic alterations in the FMR1 gene. This will include a series of investigations into the consequences of moderately expanded CGG repeats (premutations) that have been linked to premature ovarian failure and a late onset neurodegeneration. An Administrative Core will be proposed to facilitate interactions among the four research laboratories and the two institutions, and funding is sought to expand core services currently provided by the Baylor College of Medicine MRRC Mouse Neurobehavior and Synaptic Plasticity Core directed by Drs. Richard Paylor and David Sweatt. Additional funding will allow the core to expand services and to characterize the increased numbers of models anticipated to be created in the proposed Center. The four principal investigators proposing projects are Drs. David Nelson and Richard Paylor of Baylor College of Medicine, and Drs. Stephen Warren and Stephanie Sherman of Emory University. Each of these investigators has developed a strong track record of research into fragile X syndrome, and the group is now in a unique position to investigate this novel pathogenic component of fragile X syndrome. Dr. Sherman will investigate the epidemiology of the human male premutation phenotype that involves late onset tremor and cognitive decline. Dr. Nelson will develop mouse models to study effects of premutations and FMR1 gene overexpression. Dr. Warren will investigate proteins that bind selectively to expanded CGG and which may be important to premutation disease as well as fragile X syndrome, and Dr. Paylor will focus on improved methods for characterizing mouse models of fragile X syndrome and their response to treatment. [unreadable] [unreadable]